[Koha] Error reindexing biblios with zebra

Hello, can you help me to solve this problem? : when I start indexing the catalog with the instruction : perl -I /usr/share/koha/lib /usr/share/koha/bin/migration_tools/ rebuild_zebra.pl -v -b -r -run-as-root it sends me back to the end the following error : Entity: line 2355661: parser error : XML declaration allowed only at the start of the document <?xml version="1.0" encoding="ISO-8859-1"?> zebraidx(8685) [warn] extract error: generic and half of the catalog is not indexed. I use koha 16.05. thank you. BENBARRAD Tajeddine Ingénieur d'État en Génie Informatique Tél: 06 64 928 697